1. Field of the Invention
This invention relates generally to computer graphics, and more particularly to a scheme for sharing data lines in a multi-functional handheld device.
2. Description of the Related Art
The number of cellular phone users in the U.S. is now estimated at about 17 million and continues to grow at a rate exceeding 20 percent per year. Most of this growth in use has occurred in and around cities and towns with populations of 20,000 or more and has caused saturation of the channels available for cellular communication in many of these urban areas. Cellular service zones servicing about eight-hundred cellular telephone communications have decreased in size from several miles in diameter to a few hundred meters in diameter as the density of cell phone users has increased apace in urban and suburban areas.
To increase market share, cellular phone manufactures have increased features available on a cell phone, such as providing a color RGB (red, green, blue) panel display. As will be apparent to those skilled in the art, RGB is a color model used for generating images (still or video) on a display screen. Additionally, cellular phones are being provided with multi-functional capabilities. For example, cellular phones are now available that include the capability to function as a digital camera. Thus, the lines separating cellular phones and other handheld devices, e.g., digital cameras, personal digital assistants, pagers, etc., are becoming blurred. Moreover, features such as enabling a user to choose between multiple ring tones, are popular with consumers.
FIG. 1 is a simplified schematic diagram illustrating the configuration of the data lines for a multi-functional hand held device. Device 100 includes two sections 102 and 104 with data lines 116, 118 and 120 enabling communication between the two sections. For example, device 100 may be a cellular flip-phone where section 102 includes display controller 108 and central processing unit (CPU) 106, as well as a battery. Section 104 includes panel module 110, camera module 112, and external memory module 114. In order to control the peripherals of section 102, separate data lines are used for each peripheral module. That is, 18 data lines are used for panel module 110, 8 data lines are used for camera module 112, and 8 data lines are used for external memory module 114. In addition to the data lines, the dual section configuration uses separate control lines for each peripheral to provide control information between the two sections. For example, parallel panel module 110 may require 4 control lines, while camera module 112 and external memory module 114 are each associated with one control line.
Hence, the prior art dual section configuration requires about forty signal lines to provide control and data for the dual sections 102 and 104. As can be appreciated by those skilled in the art, each signal line requires an input/out (I/O) pad on either display controller 108 or CPU 106. Thus, forty signal lines require forty I/O pads, which greatly increases power consumption and routing complexity. Furthermore, the greater the number of lines routed between the two sections increases the size of the printed circuit board (PCB) to which the signal lines are connected. Another shortcoming of the large number of lines routed between the sections is that the durability of device 100 suffers due to the sheer number of lines contained by a flex cable running between the two sections. That is, as the number of signal lines increases, the manufacturing costs increase and the robustness of the device suffers.
In view of the foregoing, there is a need for minimizing the number of lines running between the controllers and the peripherals while maintaining the multi-functional capability of the handheld device.